Process of drying electric cables.



UNITED sTATEs PATENT yoEEroE WILLIAM B. HALE, COMPANY,

OF MEXICO, )I

XICO, ASSIGNORl TO WESTERN ELECTRIC OF CHICAGO, ILLINOIS, A CORPORATIONOF ILLINOIS.

PROCESS OF DRYING ELECTRIC CABLES NQ.A 851,747.

To all 1071/0711/ if i12/tty concern:

Be it known that I, IVILLIAM B. HALE, a

. citizen of the United States, residing at Mexvtromotive force ordifference .duct-ors, and the ico city, Mexico, have invented a certainnew and useful Improvement in Processes of Drying Electric Cables, ofwhich the following is a full, clear, concise, and exact description.

My invention relates to a process of drving `the coresof electriccables, and has for its object to provide an improved method which willbe simple, rapid, economical and effective.

The common method of drying cables involves the passage of a strongcurrent through the conductors thereof. to heat the cable sufficientlyto vaporize the moisture contained therein, the vapor being thenwithdrawn by means of an air pump applied to the end of the cable. Thisprocess, besides requiring the use of special apparatus, is somewhatslow and expensive.

In accordance with my invention, an elecof potential is establishedbetween different conductors of the cable sufficient to cause a flow ofcurrent through the moisture remaining in the insulating medium whichseparates said conmoistureis thereby electrolytically decomposed. Asdecomposition progresses' the insulation resistance gradually increasesand in order to maintain a flow of current strong enough for suchdecomposition, y(that is, above the critical value required forelectrolysis) the impressed elecy current necessary tromotive force maybe gradually raised, but not, of course, beyond the dielectric strengthof thel cable. If required, in some cases, the to carry on the processof electrolysis may be further maintained by temporarily reducing theresistance of the path across the insulation by means of heat, which maybe developed either in the conductors of the cable by current flowingtherein, orin the dielectric itself by the applica.- tion of analternating electromotive force.

In the accompanying drawing I have illustrated one of a number ofarrangements of apparatus which may. be adopted in practicmg my process.

1 is a telephone cable of the well known type comprising a certainnumber of conductors twisted into pairs, formed 4into a core and coveredwith a lead sheath. In the Speccaton of Letters Patent. Anelicationfilati March 12, 1906. Serial No. 305,73'8.

required value.

Patented Apru so, 190'?.v

divided into groups 2 and 3, each of said groups comprising a conductorfrom'each pair in the cable. The two groups are connected to a requiredrange of voltage, a connected to each terminal. Regulating the voltageby means of a field regulator 6 or otherwise, so that the voltmeterfconnected across the terminals indicates' an electromot-ive force' ofsay one hundred volts, the voltage may be gradually increased, atintervals of half an hour or so, as the insulation resistance rises, dueto the decomposition of moisture, until said resistance is increased tothe This may take say from two to six hours. The increase in voltage is,of course, limited by the dielectric strength or breaking-down point ofthe cable bein(r dried; and if the insulation resistance is, stil belowthe desired value when this limit is approached, the intensity ofcurrent required forelectrolysis may then be' further maintained bytemporarily increasing theconductivit y of the moisture remaining in theinsulating medium, by means of heat. This may be produced by applying analternating e. m. f. from.a suitable generator to the two groups ofwires 2, 3, to develop lthe heat in the dielectric itself by molecularaction set up therein; or strong current may be passed through some orall of the conductors of the cable toheat said conductors by the 12Reffect. To facilitate the drying out of the cable any or all of theforegoing ymeans may be employed; but ordinari y a cable would havesufficient dielectric strength to witlistand the voltage required toproduce the necessary elect-rolyzing current,without resorting to theheating process.

Although I have chosen to illustrate my one group bein(r process .bydescribing its application to a cable of the above mentioned type, itwill readily be understood that it is e ually` applicable to otherforms. Mqreover, t 1e disposition of the wiresdescribed herein is onlyone of the many arrangements that may be employed. For example, theelectrolyzing current ma be passed from all the wires to the metallicsheath of the cable, from one layer of wires to another, from one wireto another, or from any group of wires to a single wire or to anothergroup of wires.

By theprocess herein described, the insulation resista-nce of a cablewhen exceedingly generator capable of giving the IOO ' which consists induct-ors, sufficient to electrolyze the moisture jloW.,

raised to meet Whichconsists in establishing a iiow of curmit themaintenance of said current above the critical value for electrolysis. v

5. The process of drying electric cables which consists in establishing,by an iml pressed electromotive force, a flow of current through theinsulating medium of said cable, 'such current being sufficient toelectrolytically decompose the moisture therein, lan heating said mediumto temporarilyincrease its conductivity to a point which will permit themaintenance of said current at the required intensity for suchdecomposition without increasing the impressed electromotive force to apoint beyond the dielectric resisting strength of the cable, saidheating being produced due to the presence of moisture, may be standardrequirements. he removal of the moisture furthermore inaterially reducesthe capacity of thecable.

1. The process of drying electric .cables maintaining a flow of electriccurrent through the insulating material of the cable, of sufiicientstrength .to electrolyzethe moisture therein.

.2. The process of drying electric' .cables, which consistsinestablishing a'difference of l potential'between derent conductors ofthe l cable, and thereby causing a flow of current through theinsulation surrounding said conductors sufficient'to decompose themoisture therein. j

3. The process oi' drying electric cables Whichconsists in establishingan electronic-v tive force -between different conductors of the. cable,thereby causing a now of current through the insulation surrounding saidconby the application of a suitable electromotive force to theconductors' of said cable.

6. The process of drying electric cables, which consists in establishinga iow of current between different conductors of the cable through themoisture remaining in the insulating medium, said current beingsufficient to cause electiolytic decomposition of such moisture, andheating said insulating i medium to temporarily reduce the insulation iresistance of the cable so as to increase the current which will iiowunder a given electroniotive force.

therein, and progressively increasing the impressed electromotive forceas t-he insulation resistance rises, to maintain t-he current iioivabove the critical value for electrolysis.

. 4. The process' of drying electric cables,

`rent between different conductors of the cable through the moistureremaining in the my name this 26th day of February A. D..

insulating medium, said current. being suiiil 1906. f

cient to cause electrolytic decomposition of WILLIAM B. HALE. Asuchmoisture, and'electricall'y heating said Witnesses:

insulating medium to temporarily increase THOMAS G. NEE,

the' conductivity otsaid moisture so as to per- FERNANDO GIL.

In Witness whereof, I, hereunto subscribe-

